I've finnaly reached the point that I can add some color to my vertices. But now I want to improve my FPS rate. Here is the current situation. I have a large number of vertices (~200000) , and each of them can be in one of ~150 classes. Each class is differenced by it`s color. I'm currently drawing my vertices like:
glEnableClientState(GL_VERTEX_ARRAY)
glBindBufferARB(GL_ARRAY_BUFFER_ARB, self.bufferVertices)
glVertexPointer(3, GL_FLOAT, 0, None)
glEnableClientState(GL_NORMAL_ARRAY);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, self.bufferNormals)
glNormalPointer(GL_FLOAT, 0, None)
glEnableClientState(GL_COLOR_ARRAY)
glBindBufferARB(GL_ARRAY_BUFFER_ARB, self.bufferColors)
glColorPointer(3, GL_FLOAT, 0, None)
glDrawArrays( GL_POINTS, 0, len(self.vertices) / 3 )
Everything works fine and the FPS is ~60. All my buffers are generated only at init time. But now the colors that represent each class will change rapidly, once about every millisecond. With that the colors will also change so I would have to recreate my color buffer for each draw, and for 200000 vertices I have a feeling the FPS will be close to 0. The fix I'm trying to implement is to keep a fixed color buffer, but instead of the actual colors, they would retain a pointer to the class it`s represented by. That way, only the 200 colors of the classes will change. Problem is I don't know how this could be implemented in OpenGL. Is this doable ? Any pointers in how to do this?
Instead of colors the classes should set a 1D texture coordinate, then instead of changing that huge dataset you have to replace only parts of the texture. To avoid texture sampling interpolation set the texture into GL_NEAREST filtering mode, and sample the texture in the vertex shader per vertex (i.e. no per fragment texture sampling as you'd do usually).